Physical distancing rules: Not as simple as they seem

Social distancing signs and lanes are set up at the MRT3 North Avenue station in Quezon City on Wednesday, May 13, 2020 as the mass transport system prepares for its resumption of operation under the modified enhanced community quarantine (ECQ). INQUIRER PHOTO / GRIG C. MONTEGRANDE

The physical distancing rule of 1 to 2 meters to prevent transmission of the new coronavirus is based on “outdated science and experiences of past viruses,” researchers claim in a new study.

In the study published in BMJ, formerly known as the British Medical Journal, researchers from the University of Oxford, St. Thomas’ Hospital, and Massachusetts Institute of Technology say setting physical distancing at 1 to 2 meters “oversimplifies and underestimates” risks.

In their paper, Oxford researcher Nicholas Jones and his colleagues make an example of how infection can be easily transmitted in places such as meat packing plants despite physical distancing.

Environmental influences

“Environmental influences are complex. For example, in meat packing plants … outbreaks have been attributed to the combination of high levels of worker contagion, poor ventilation, cramped working conditions, background noise (which leads to shouting), and low compliance with mask wearing,” the researchers say.

They emphasize the role of droplet sizes and exhaled air that carries these in coronavirus transmission.

Evidence suggest that smaller airborne droplets laden with the COVID-19 virus can travel more than 2 meters, but sometimes the reach is even farther, they say.

“Breathing out, singing, coughing and sneezing generate warm, moist, high momentum gas clouds of exhaled air ventilation flows, keeps them concentrated, and can extend their range up to 7 to 8 meters within a few seconds,” they say.

Because of these findings, the researchers say setting physical distancing rules needs to take into account multiple factors that affect risk, including type of activity, indoor or outdoor setting, level of ventilation, and whether face coverings are worn.

The viral load of the emitter, the duration of exposure, and the susceptibility of an individual to infection are also important factors to consider, the researchers say.

Highest in Southeast Asia

In the Philippines, the Department of Health (DOH) emphasizes physical distancing and the wearing of face coverings to slow down the spread of the coronavirus.

The country has the highest number of coronavirus infections in Southeast Asia, with the capital region, Metropolitan Manila, as the epicenter of the local outbreak.

On Thursday, the DOH reported 1,987 additional infections, bringing the national tally to 228,403 cases. It was the first time the country recorded fewer than 2,000 new cases in a single day since July 29.

The DOH said it removed 24 duplicates from the total case count. It also said three cases that were previously reported as recovered had been correctly marked as fatalities after final validation.

The department said 818 of the additional cases were from Metro Manila, 153 from Cavite, 125 from Laguna, 122 from Negros Occidental, and 78 from Rizal.

It reported 880 new recoveries, pushing the total number of COVID-19 survivors to 159,475. The death toll, however, increased to 3,688 with the deaths of 65 more patients.

Of the newly reported fatalities, two died in September, 55 in August, six in July, and one each in April and June.